Methods - Neurophysiology of Movement
- Neurophysiology of Movement
Electroencephalography (EEG) enables noninvasive measurement of brain activity by deriving voltage fluctuations from electrodes placed on the head. The relatively small brain signals (5-500 µV) are amplified by a measurement amplifier. In the nemolab, we use a mobile 32/64 channel system (LiveAmp) as well as a 16-channel system (V-Amp) from BrainProducts with active Ag/AgCl electrodes that are attached with the help of an electrode cap (actiCap, BrainProducts). Active electrodes have an additional small amplifier built directly into the electrode making measurements less prone to artifacts. This allows us to investigate large and/or fast movements very accurately. With the EEG, we mainly measure the event-related potentials that can be observed during the execution and learning of movements (e.g., Bereitschaftspotential, error-related negativity, feedback-related negativity, P300).
The Department of Psychology and Sports Science has a 3 Tesla Siemens Prisma Scanner at its disposal in the Bender Institute of Neuroimaging (BION). Functional magnetic resonance imaging (fMRI) is an imaging technique that can display brain structures based on oxygenation of the blood. We use fMRI to investigate neural mechanisms of movement and movement simulation.
Functional near-infrared spectroscopy (fNIRS) is a noninvasive measurement of concentration changes of oxygenated and de-oxygenated hemoglobin in the blood. We are using this method to deduce changes in cortical activity. Near-infrared light is emitted at a specific region on the scalp. The reflection rate depends on the oxygenation level and can be used to recalculate concentration changes. This method enables us to observe cortical activity even under realistic movement conditions, because it is relatively robust with respect to movement artifacts. It can also be used to quantify oxygenation in skeletal muscles.